Protective helmet



FIG. 1 is a front perspective view of a protective helmet showing our new design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a rear view thereof;

FIG. 6 is a side view thereof; and,

FIG. 7 is a bottom view thereof.

The details shown in broken lines form no part of the claimed design. The dash-dot-dashed lines represent boundary lines. 

CLAIM The ornamental design for a protective helmet, as shown and described. 